Impulse controlled speed-responsive relay



P 1962 H. DOMANN 3,053,243

IMPULSE CONTROLLED SPEED-RESPONSIVE RELAY Filed Oct. 28. 1960 2 Sheets-Sheet 1 & II II I I I I I P L10 F/G. 4

l I I I l I Sept. 11, 1962 H. DOMANN IMPULSE commons]: SPEED-RESPONSIVE RELAY 2 Sheets-Sheet 2 Filed Oct. 28. 1960 Fig.5

114 141T 735 Mi: Fig. 7

United States Patent 3,053,243 MPULSE CUNTRQLLED SPEED- RESPONSIVE RELAY Helmut Domann, Stuttgart, Germany, assignor to Robert Bosch G.m.h.H., Stuttgart, Germany Filed Oct. 28, 1960, Ser. No. 65,797 Claims priority, application Germany Get. 17, 1959 14 Claims. (Cl. 123-179) The present invention concerns an impulse controlled speed-responsive relay, preferably with delay characteristics and especially suited for being used in a motor vehicle for blocking the starter system under certain conditions.

This is a continuation-in-part of my copending application, Serial No. 63,014 filed October 17, 1960, entitled Impulse Controlled Speed-Responsive Relay, now abancloned.

in order to be able to control electrical or mechanical operations of certain apparatus in motor vehicles depending upon the varying rotary speeds thereof it is necessary to provide relay devices which are actuated to change from their idle condition to their operative condition whenever the engine reaches a predetermined rotary speed. In a similar manner a relay may be desirable which is caused to change between its idle and operating conditions whenever the engine speed drops below a predetermined minimum. It has been found that the accuracy and sensitivity of such relays is increased if the energizing currents introduced into the relay follow precisely the variation of the rotary speed of the engine in linear relationship.

It is further desirable to provide for a relay arrangement Which would prevent damage to the starter gears when after an unsuccessful attempt to start the engine the starter motor should be energized again before the engine and the flywheel carrying one of the starter gears have returned to standstill.

It is therefore a main object of the invention to provide for a relay arrangement of the type set forth in which the energizing currents for the relay follow linearly the frequency of control pulses applied thereto and depending upon the rotary speed of the engine.

It is another object of the invention to provide for a relay arrangement of the type set forth in which a delay of the relay action is obtained upon de-energization of the starter motor..

it is a further object of this invention to provide for an arrangement as stated above which is highly sensitive and accurate and reliable in operation.

With the above objects in view an impulse controlled speed-responsive relay arrangement for motor vehicles having an engine operable at varying rotary speeds comprises, according to the invention, in combination, pulse generator means operatively connected with the engine for furnishing pulse sequences of varying frequencies corresponding to the varying rotary speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct current voltage, with a resistor connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectifier means, condenser means being connected in parallel with said rectifier means across said collector-base circuit; circuit means connected between said pulse generator means and said collector-base circuit for application of said pulse sequences thereto; and relay means including coil means and cooperating contact means movable between idle and operative positions depending upon energization of said coil means and adapted to control accordingly an operating circuit that may be connected in circuit with said contact means, said coil means being connected at one end mined minimum value.

thereof with the collector of said transistor means, whereby said coil means will be energized depending upon the pulse frequency furnished by the pulse generator means corresponding to the speed of the engine.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a schematic diagram of one embodiment of the invention showing the circuitry and the engine and pertaining elements;

FIG. 2 is a diagram illustrating the relation between relay energizing currents and rotary speed of the engine;

FIG. 3 is another diagram illustrating the form of an energizing current in relation to time;

FIG. 4 illustrates a modification of the embodiment of FIG. 1 by illustrating a second form of one portion of the circuitry illustrated in FIG. 1;

FIG. 5 is a schematic diagram of a further modification of the embodiment of FIG. 1 including pulse-operated delay means;

FIG. 6 is a diagram showing a modification of a portion of the circuitry of FIG. 5; and

FIG. 7 is a diagram illustrating a modification of FIG. 6.

The relay arrangement according to FIG. 1 is designed for being used in a motor vehicle which has a four-cylinder four-stroke engine It The engine is equipped with an electric starter motor 11 and with a braking throttle 14 located within the exhaust channel 12 which throttle may be utilized, e.g. during long downhill rides for assisting or relieving the standard brake system of the vehicle by turn ing the throttle 14 from the illustrated open position toward or into its closing position with the aid of an electromagnetic actuator described below.

The actual relay arrangement according to the invention is shown within the dotted frame 20. This type of relay arrangement has the double purpose of automatically turning the braking throttle 14 to its open position whenever the rotary speed of the engine drops below a predeter- Se'cond, the arrangement is designed to prevent the starter motor 11 from being put into operation as long as the crank shaft (not shown) of the engine is in rotation or at least is rotating at a speed above a very low predetermined maximum. The entire arrangement 2% is controlled by current pulses which are furnished, e.g., by the conventional high voltage ignition system cooperating with the engine 10. The ignition system comprises an ignition coil 21 having a primary Winding 22, an iron core 23 and a secondary winding 24, further a distributor 25 and an interrupter switch 28 operated periodically by a four-cam member 27, the latter and the rotary arm of the distributor 25 being driven directly or indirectly by the crank shaft of the engine. The ignition system further comprises an ignition condenser 29 as shown. The outer ends of the primary winding 22 and the secondary winding 24, respectively, of the ignition coil 21 are connected with each other and their junction point across the primary winding 35 of a trans former, described below, with the positive terminal of a storage battery 36. This battery serves as source of direct current energy both for the ignition system and the other devices shown in FIG. 1 including the starter motor 11.

The above mentioned transformer 30 is part of the relay arrangement 20. The primary winding- 35 is mounted on an iron core 38 and the secondary winding 37 is connected at one end with the base B of a p-n-p transistor 40 Whose emitter electrode is connected via a tifier 43 whose input electrode is connected with the collector electrode C of the transistor 40. Thus the secondary winding 37 is connected in the collector-base circuit of this transistor. The base of the transistor 40 is also connected via a resistor inserted between junction point 40 and terminal 46, with ground, i.e. with the negative terminal of the battery 36.

A first relay coil 47 cooperating with a normally open movable contact 63 is connected at one of its ends also with ground via terminal 46 while the other end of the coil 47 is connected with the collector C of the transistor 40 via junction point 40". However, the collector-base circuit of the transistor contains furthermore a chargeable condenser 48 connected in parallel with this circuit be tween the junction points 40 and 40". As can be seen the relay coils 47 and 49 are actually connected in series with each other between the terminals of the battery 36, the junction point between the coils 47 and 49 being connected to the collector C of the transistor 40.

The first mentioned movable contact arm 63 and the other movable contact arm 50 are both connected with the positive line 42. The relay 47, 63 serves to control the circuit of the starter motor 11 while the relay 49, 50 serves to control the circuit of the brake throttle mechanism mentioned above. For this purpose the contact arm 63 is arranged to engage, upon energization of the coil 47, a stationary contact 65 connected with a terminal 66 and from there via line 62 and starter switch 60 with the starter motor 11. The contact arm 50' is arranged to engage, upon energization of the coil 49, a stationary contact 52 connected with terminal 53 and from there via a switch 54 with an electromagnet 55 adapted to move the brake throttle 14 into closed position when energized, and to permit the throttle 14 to return, under the action of means not shown, to its open position when relay coil 49 is de-energized. On the other hand, closing of the starter switch would not close a circuit for operating the starter motor 11 unless the coil 47 is energized and contacts 63 and 65 are moved into engagement. As Will be shown, this can only take place when the engine is not rotating at all or only extremely slowly. A relay switch 61 may be interposed between the starter switch 60 and ground for indirectly controlling the starter motor 11.

For the purpose of explaining the operation of the arrangement, it should be considered that the ohmic resistance of the relay coil 49 is substantially equal to that of the relay coil 47. As long as the engine is at standstill, the transistor 40 is capable of carrying a strong current J across the coil 47 because its base electrode B is connected via resistor 45 with ground, i.e. with the negative terminal of the battery 36. Consequently the coil 47 is energized under this condition so that the movable contact 63 is forced into engagement with the stationary contact 65. Thus the starter motor 11 can be actuated by the closing of the starter switch 60. Now the crank shaft of the engine will be rotated at a starting speed of n r.p.m. so that the engine 10 can start its own operation. The cam member 27 mounted on the cam shaft 26 and thus rotating at half the rotary speed of the crank shaft will cause the interrupter contact 28 to move four times per revolution of the cam shaft 26 to open position. Every time the interrupter contact 28 opens the circuit, the current flowing across the primary winding 22 of the ignition coil 21 is interrupted and consequently a voltage pulse is induced simultaneously with said interruptions so that the condenser 48 is charged with every pulse by an equal amount of energy. As the charge of the condenser 48 increases the current J flowing through the emitter-collector circuit of the transistor 40 and through the relay coil 47 decreases. Since the consecutive charging pulses of constant amplitude follow each other at increasingly smaller intervals as the rotary speed of the engine increases, this sequence of pulses will set up in the condenser 46 a potential which increases linearly with the increasing rotary speed of the engine, and therefore the increasing rotary speed of the engine will cause the arithmetic mean value 3 of the above mentioned energizing current J to decrease linearly as shown in the diagram of FIG. 2.

In the diagram of FIG. 2 in which current values are indicated as ordinates and rotary speed as abscissae, the line 76 indicates that current value 1,, which would not suffice any more to energize the relay coil 47 sufiiciently for holding the movable contact 63 in engagement with the contact 65. The intersection of line 76 with the current line J corresponds to the rotary speed n which is still below the idling speed n of the engine. This means that upon an increase of the engine speed beyond n the contact 63 will open and interrupt the starter circuit. The line 72 in FIG. 2 indicates the current value J required to energize the relay coil 47 sufficiently for moving the arm 63 into engagement with contact 65. The value I is reached by the current J flowing through the transistor 46 when the engine speed drops to a speed n below the idling speed n and at which speed the engine could not continue to operate by itself and therefore would come to a standstill. The capacity of the condenser 48 being of the order of about pi. and the relay coil 47 located in the discharge circuit of the condenser having a certain resistance to which is added the resistance of the resistor 45, the potential at the condenser 48 is bound to follow the decrease of rotary speed of the engine with a time delay of more than one second.

The second relay with coil 49' behaves in a manner just opposite to the behavior of the above described relay which is to block the operation of the starter at engine speeds above a certain absolute maximum. The response of the relay coil 49 to varying conditions is due to the fact that it is connected in parallel with the emitter-col lector circuit of the transistor 40. This emitter-collector circuit constitutes during standstill of the engine a very low resistance in parallel with the relay coil 49 so that during standstill of the engine practically no current can flow through the coil 49. Only when the potential at the condenser 48 is raised by a rapid sequence of charging pulses induced in the secondary winding 37 whereby the transistor 40 is rendered non-conductive to an increasing degree, an increasing energizing current J is capable of flowing through the relay coil 49. The mean value of this current is indicated in FIG. 2 by the dotted line 75 in dependence upon varying rotary speeds. The current value I sufiicing to cause movement of the contact arm 50 into engagement with contact 52 is so chosen that the current J can reach such value only when the rotary speed increases to the value 11 which value is above the idling speed n of the engine. However, when the rotary speed of the engine drops to a speed n the relay coil 49 will be de-energized so as to permit the arm 50 to return to idle position. The speed n is below the above mentioned speed n but sufiiciently above the idling speed n of the engine.

On one hand, it is advantageous for the operation of the starter controlling relay 47, 63 if the speed n causing interruption of the starter circuit is a substantial amount above the speed n which would cause again closing of the contact arrangement 63, 65, on the other hand it is desirable that the other relay controlling the position of the brake throttle 14 causes closing of the throttle 14 at a speed which is as little as possible above the idling speed n of the engine, but carries out this function when the speed of the engine increases above the idling speed. Moreover, the last mentioned relay is intended to interrupt the circuit of the throttle control 55 again, when the vehicle is slowed by application of the regular brake, at a speed which is only a small amount above the idling speed n This sensitivity can be obtained by utilizing the waviness of the current 1 which flows through the relay coil 49. For this purpose the relay 49, 50 is so dimensioned that the difference be tween the current values I and I is only slightly larger than the amplitude of the waviness of the current J In FIG. 3 the zig-zag line 77 illustrates diagrammatically the fluctuation or waviness of the current I As can be seen the highest and lowest values of the current I are distributed symmetrically with the line 78 which represents the mean value of the current. This mean value of the current I should be available at a speed 11 which i slightly above the idling speed 11 FIG. 3 contains further a line '79 representing the above mentioned current value I and a line 80 representing the lower current value I The energizing current J of the relay coil 49 fluctuates between the above mentioned two values, but at the above mentioned speed 12 the value I is not reached thereby and the current J never falls short of the value I As soon as, however, the engine is accelerated beyond the speed in, the current curve 77 is shifted in upward direction in the diagram. of FIG. 3 so that it assumes the position 77 shown in dotted lines and thus intersects with the line 79. The areas of intersection are emphasized in the diagram and the corresponding current pulses are sufficient to energize the coil 49 and to move the contact 5%} into engagement position. On the other hand, if the speed slightly decreases, the current line 7'7 will be shifted in downward direction to the position shown by a dotted line '77 in which case this current line intersects with the line 86 resulting in the emphasized intersection areas whereby the effective current enters the range below the value J and consequently the relay contact 59 is permitted to return to its idle position. In this manner it can be arranged that in spite of a comparatively great difference between the current values I and I already from small speed increases above or decreases below the speed :1 the relay 49, St} is caused to respond so as to move the contact 50 in one or the other of its positions and to remain therein. Practically speaking, the just mentioned relay carries out the switching operation at a uniform predetermined speed 11 with great precision and irrespective of whether this speed a has been reached during acceleration or during slowing down of the engine. Therefore it is possible to select for the critical speed 11 a speed value which is very closely above the idling speed n FIG. 4 illustrates a modification of the arrangement surrounded by the frame 20 in FIG. 1. Within the frame 26' of FIG. 4 a modified relay arrangement is shown which is particularly suitable for controlling the starter circuit. The portions of FIG. 1 outside the frame 29 have been omitted in FIG. 4 but should be assumed to be arranged analogously for cooperation with the specific arrangement of FIG. 4.

In FIG. 4 only a battery 85 is shown which corresponds to the battery 36 in FIG. 1, and an interrupter contact 81 which corresponds to the interrupter contact 28 of FIG. 1. A protective resistor 82 is connected between the interrupter contact 81 and the one end of the primary winding 83 of a transformer 84. The primary winding 83 is accordingly connected between the terminals of the battery 85. The secondary portion of the transformer 84 comprises two separate secondary Windings 86 and 87 connected in series with each other, the junction point between the windings being connected to one side of a condenser 91. The other side of the condenser 91 is connected via rectifiers 33 and 89, respectively, with the outer ends of the secondary windings 86 and 87, respectively. At the same time the other side of the condenser 91 is connected with the collector C of a first transistor 92. Whenever the interrupter 81 closes or opens the primary circuit, charging potential is induced in the secondary windings 86 and 87, respectively, and the resulting voltage pulses are applied in both cases to the condenser 91. This has the same effect as the charging of the condenser 48 in FIG. 1 since the condenser 91 is also connected in parallel across the base-collector circuit of the transistor 92.

A further difference between the arrangements of FIG. 1 and FIG. 4 resides in the fact that the emitter E on the transistor 92 is connected with the base of a further p-n-p transistor 93 intended to act as an amplifier. Both transistors 92 and 93 have their collectors connected in parallel with each other with a junction point between the relay coil 90 and a resistor 95, the resulting series combination of coil 90 and 95 being connected between the terminals of the battery via the grounded terminal 97. In the same manner as in FIG. 1, the base B of the transistor 92 is connected with the grounded terminal 97 via a resistor 96.

Due to the provision of two secondary windings 86 and 87 in the manner shown in FIG. 4 the entire arrangement obtains greater sensitivity and accuracy of operation which is still enhanced by the cascade connection of the transistors 92 and 93 resulting in a substantial current amplification.

The modification of the relay arrangement according to FIG. 4 is particularly useful for blocking the starter circuit in those cases where the starter current is so great that the output voltage of the battery drops considerably during the operation of the starter motor. While in the arrangement of FIG. 1 the contacts 63, 65 cooperating with the coil 47 are directly connected in the starter circuit and while there the coil 47 is connected in series with the emitter-collector circuit of the transistor 49, the arrangement according to FIG. 4 does not entail the danger that upon actuation of the starter switch 60 the drop of the battery voltage due to the high starter current would cause the relay 47, 63 to be tie-energized and moved to open position so as to interrupt the starter circuit with the consequence that only after the battery voltage is restored to its normal value the relay switch 63, 65 would be closed again. Thi possibility can be safely avoided by connecting the rest contacts of the relay containing the coil in the control circuit of the starter control relay 61 and in parallel with the impulse controlled transistor or transistors.

It has been found that sometimes difficulties develop in practical operation of relays of the general type described above, particularly of a relay which controls the operation of the starter motor. It may occur that the operator first starts the engine by operating the starter button or switch, but releases the button or switch before the engine itself had an opportunity of starting, and then the operator may operate the starter button or switch before the crank shaft of the engine and the flywheel which carries one of the starter gears have returned to standstill. In such cases it is easily possible that at least one of the gears suffers damage which would entail costly repairs.

In order to prevent such damages the above arrangements may be modified advantageously as Will be described herebelow. The effect of these modifications is that the relay which controls the starter operation returns to its circuit-blocking condition also when the starter motor is disconnected or de-energized at a rotary speed of the engine which is so low that in the above described arrangements the just-mentioned relay would be in its circuit closing condition in view of the respective very low rotary speed of the engine.

The desired effect is obtained according to the invention by providing for a delay of the relay action during its tendency to return to its normal circuit-closing condition, the delay being derived from the inductive voltage peaks developing in the starter circuit upon the disconnection of the starter and said voltage peaks being ap plied to the condenser in the described relay circuit so as to increase the charge potential thereof existing at the moment of disconnecting the starter.

The above-mentioned starter circuit usually contains a starter relay which controls the starter motor and is, in turn, controlled by the relay arrangement according to the invention. Advantageously one end of the coil of the just-mentioned starter relay is connected, according to the invention, via a resistor and a rectifier with one of the two plates or sides of the above-mentioned condenser. A particularly effective arrangement is obtained if the transformer which transmits the controlling impulses derived from the rotation of the engine to the transistor circuit of the relay arrangement is provided with a second primary winding which is connected via a rectifier and another resistor with that end of the winding of the starter relay which is not connected to ground.

Several modifications of the general relay arrangement and providing for the above-mentioned desirable effect are illustrated by FIGS. -7.

As can be seen from FIG. 5 a four-cylinder diesel engine is provided with a starter motor 111 which may be coupled with the crank shaft of the engine by gears 148, 149. The starter motor 111 is controlled by a starter relay 113 having a coil, not shown in FIG. 5, which is connected with the storage battery 112 by the positive line 142 and the negative 144 which extends via terminal 143, relay contacts 140 and 141 and the starter button 114 to ground and thus to the negative terminal of the battery 112. The power supply lines connecting the battery 112 with the motor 111 and controlled by suitable contacts in the starter relay 113 are not shown because they are not necessary for understanding the invention.

Since a diesel engine operates without an ignition system, the pulse generator means in the present example comprise an interrupter switch arrangement including a four-lobe cam member 116 mounted for rotation on the crank shaft of the engine 110 and cooperating with a movable switch arm 117. In closed position the contact arm 117 closes a circuit from the negative terminal of the battery 112 via ground, through a limiting resistor 119, through the primary winding 122 of a transformer 123, the winding 122 being connected between terminals 120 and 121, and from terminal 121 back to the positive terminal of the battery 112. The transformer 123 carries on its iron core 124 a secondary winding 125. One end of this winding is connected with the base electrode B of the transistor 130 the emitter electrode E of which is connected to a positive line 131 ending also at the terminal 121 and therefore being connected to the positive terminal of the battery 112. The other end. of the secondary winding 125 is connected via a rectifier 132 with the collector electrode C of the transistor 130, said collector electrode being also connected with one end of the relay coil 135 which operates the above-mentioned relay contact 140. The other end of the relay coil 135 is connected to the positive line 131 and is, therefore, located in the collector-emitter circuit of the transistor 130. As can be seen the secondary winding 125 forms part of the collector-base circuit of the transistor 130. However, a condenser 136 is connected in parallel across the collector-base circuit between the junction points 136' and 136". The condenser 136 has preferably a capacity of 100 ,uf. Additionally, between the junction point 136 and a grounded terminal 137 is connected a resistor 138 which is so dimensioned that when the transistor 130 is in nonconductive or almost non-conductive condition a current can flow over the relay coil 135 which is sufficient for moving the relay switch contact 140 from its normally closed position to open position.

Up to this point the relay arrangement surrounded by a dotted frame line 201 is similar to the corresponding arrangement in FIG. 1. However, as can be seen from FIG. 5, the base electrode B of the transistor 130 is connected via junction point 130', a rectifier 146 and a resistor 145 with the terminal 143 in the starter circuit. The rectifier 146 is so polarized that current can pass therethrough only in direction from the terminal 143 to the base electrode B of the transistor 130.

In operation, when after closing the push button switch 114 the starter relay 113 is energized so that the operative circuit of the starter motor 111 is closed, then the starter motor 111 will be able to rotate the crank shaft of the engine 111) at a speed sufiicient for causing starting of the engine operation. As soon as the engine starts operating by itself the above described pulse generator means, due to the rotation of the cam member 116 and the resulting periodical interruptions of the circuit through the primary winding 122 by periodical movements of the switch arm 117 into open positions, a rapid sequence of current pulses is produced and applied to the transformer 123 whereby the voltage pulses induced in the secondary winding are caused to charge the condenser 136 to a comparatively high charge potential whereby the previously conductive transistor 1313 is changed to nonconductive condition in which its emitter-collector circuit constitutes a high resistance and therefore practically ineffective shunt or parallel circuit for the relay coil 135. Under these conditions the relay coil 135 is fully energized by the battery voltage via the resistor 138 as described above and is therefore capable of moving the associated switch relay contact arm 140 from its normal closed position, as shown, into open position in which the circuit for the starter relay 114 is interrupted.

It is evident from the preceding description of the embodiments according to FIGS. 1 and 4, that when the engine 110 slows down or comes to a standstill and the charging of the condenser 136 is discontinued, the transistor would return to conductive condition in which case its emitter-collector circuit constitutes a very effective bypass or shunt circuit for the coil so that the latter becomes de-energized and the relay contacts 14-0, 14 1 return to their normal closed position.

As mentioned above it is possible that the starter button 114 is released by the operator before the engine 110 has started its own operation. In this case it must be prevented that an immediately following renewed operation of the starter button 114 would cause energization of the starter relay 113 and thereby a movement of the gear 148 of the starter motor 111 into mesh with the still rotating gear 149 mounted on the flywheel of the engine 110. This is prevented by the effect of the above described series connection of a resistor 145 and rectifier 146 between the terminal 143 and the junction point 131) and with the base electrode B of the transistor 130. When the operating circuit for the relay 113 is interrupted, a strong inductive voltage pulse appears at the terminals of the not illustrated coil of the starter relay 113 which coil has a high inductivity. This voltage pulse is applied via resistor 145, rectifier 146 and junction points 130' and 136 to the condenser 1 36 which thereby obtains a very strong charge. Hereby the transistor 131] is changed to non-conductive condition whereby, for the reasons stated above, the relay coil 135 is energized and the contact is removed to open position.

Only after the just-mentioned condenser charge which was produced by the voltage pulse has been dissipated across the resistor 147 connected with the grounded terminal 137 to such an extent that the transistor 130 again becomes strongly conductive, then the relay coil 135 is again de-energized permitting the contact 140 to return to its normal closed position so that hereafter the starter relay 113 and thereby the starter itself can be energized by operation of the starter button 114. It is of great ad vantage that in this arrangement the resisors 138 and 147 located in the discharge circuit of the condenser 136 increase the discharge time of the condenser to about l to 3 seconds. This delay time which determines the period of time that has to elapse before the starter 111 can be operated again, may be adjusted without difficulty by choosing accordingly the magnitude of the resistor 147.

Now the modification according to FIG. 6 will be described. While in the example of FIG. 5 a transistor of the p-n-p type can be used because the relay contacts 140 and 141 are located in that circuit portion which during energization of the starter relay 113 is connected with ground, the transistor 166 in the arrangement according to FIG. 6 must be of the n-p-n type because in this case the relay contacts 140 and 111 are located in that portion of the circuit which is connected with the positive terminal of the battery 112. As far as the component elements of the arrangement according to FIG. 6 are identical or equivalent with those used in the arrangement according to FIG. 5, the respective component elements are marked with the same reference numerals. The magnet coil of the starter relay is marked in FIG. 6 with the numeral 161. One end of this coil 161 is connected to electrical ground, while the other end thereof is connected to the movable contact arm 140 of th relay 135. In the same manner as described in reference to FIG. 5, the terminal 143 at which the above described inductive voltage pulse appears upon release of the starter button 114, is connected via a resistor 14.5 and a rectifier 146 and junction point 13d with the base electrode B of the n-p-n-transistor 160, however in this case the rectifier 146 is polarized in a direction opposite to that employed in the arrangement according to FIG. 5.

The further modification according to FIG. 7 differs from the arrangement according to FIG. by having the advantage that the magnet coil 161 of the starter relay can be connected directly with ground and that the relay contacts 14th and 141 together with the starter button 114 are inserted in the positive line 131 leading to the positive terminal of the battery 112. In addition the arrangement according to FIG. 7 entails the further advantage over the arrangement according to FIG. 6 that instead of a comparatively expensive n-p-n transistor a less expensive but nevertheless very effective and powerful p-n-p transistor 170 can be used. In order to enable the inductive voltage peaks generated at the terminal 143 upon release of the starter button 114, as described above, to increase the charge potential at the condenser 136, the impulse transformer 171 is provided not only with a primary winding 17?. corresponding to the winding 122 in FIG. 5, and with a secondary winding 175 corresponding to the winding 125 in FIG. 5, but also with -a third winding 176 one end of which is directly connected with electrical ground. The other end of this winding is connected with the terminal 143 via a rectifier 177 and a resistor 178 and, therefore, is supplied with a strong current pulse upon release of the starter button 114. This current pulse produces in the secondary winding 175 a high voltage which serves to increase the present charge of the condenser 136 by which the transistor 170 is changed to non-conductive condition so that during a delay period ranging between 1 and 5 seconds the relay contacts 140 and 141 can move into open position.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of impulse controlled relay arrangement differing from the types described above.

While the invention has been illustrated and described as embodied in impulse controlled speed-responsive relay arrangement for motor vehicles, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. Impulse controlled speed-responsive relay arrangement for motor vehicles having an engine operable at varying rotary speeds, comprising, in combination, pulse:

generator means operatively connected with the engine for furnishing pulse sequences of varying frequencies corresponding to the varying rotary speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct current voltage, with a resistor connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectifier means, condenser means being connected in parallel with said rectifier means across said collector-base circuit; circuit means comprising transformer means having primary winding means in circuit with said pulse generator means, and secondary winding means arranged in said collector-base circuit for application of said pulse sequences thereto; and relay means including coil means and cooperating contact means movable between idle and operative positions depending upon energization of said coil means and adapted to control accordingly an operating circuit that may be connected in circuit with said contact means, said coil means being connected in parallel with the emitter-collector circuit of said transistor means between the other terminal of said source and a junction point between the collector of said transistor means and said parallel connected rectifier and condenser means, whereby said coil means will be energized depending upon the pulse frequency furnished by the pulse generator means corresponding to the speed of the engine.

2. Impulse controlled speed-responsive relay arrangement for motor vehiclm having an engine operable at varying rotary speeds, comprising, in combination, pulse generator means operatively connected with the engine for furnishing pulse sequences of varying frequencies corresponding to the varying rotary speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct current voltage, with a resistor connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectifier means, condenser means being connected in parallel with said rectifier means across said collector-base circuit; circuit means comprising transformer means having primary winding means in circuit with said pulse generator means, and two secondary winding means arranged in said collector base circuit for application of said pulse sequences thereto, one end of each of said secondary windings being connected with the base of said transistor means and with one side of said condenser means, each of the other ends of said secondary windings being connected via rectifiers, respectively, with the other side =of said condenser means and with the collector of said transistor means; and relay means including coil means and cooperating contact means movable between idle and operative positions depending upon energization of said coil means and adapted to control accordingly an operating circuit that may be connected in circuit with said contact means, said coil means being connected at one end thereof with the collector of said transistor means, whereby said coil means will be energized depending upon the pulse frequency furnished by the pulse generator means corresponding to the speed of the engine.

3. An arrangement as claimed in claim 2, wherein said coil means is connected in parallel with the emittercollector circuit of said transistor means between the other terminal of said source and a junction point between the collector of said transistor means and said parallel connected rectifier and condenser means.

4. An arrangement as claimed in claim 2, including second transistor means having its base electrode connected with the emitter electrode of said first mentioned transistor means, and having its emitter electrode connected with said other terminal of said source, while its collector is connected in parallel with the collector of said first mentioned transistor means to said one end of said coil means.

5. Impulse controlled speed-responsive relay arrangement for motor vehicles having an engine operable at varying rotary speeds, comprising, in combination, pulse generator means operatively connected with the engine for furnishing pulse sequences of varying frequencies corresponding to the varying rotary speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct current voltage, with a resistor connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectifier means, condenser means being connected in parallel with said rectifier means across said collector-base circuit; circuit means connected between said pulse generator means and said collector base circuit for application of said pulse sequences thereto; and relay means including two coil means and two respectively cooperating contact means movable between idle and operative positions depending upon energization of said coil means and adapted to control accordingly two separate operating circuits, respectively, that may be connected in circuit with said contact means, said two coil means being connected in series with each other between the terminals of said source, the junction point between said two coil means being connected with the collector of said transistor means, whereby said coil means will be energized depending upon the pulse frequency furnished by the pulse generator means corresponding to the speed of the engine.

6. Impulse controlled speed-responsive relay arrangement for motor vehicles having an engine operable at varying rotary speeds, comprising, in combination, pulse generator means operatively connected with the engine for furnishing pulse sequences of varying frequencies corresponding to the varyin rotary speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct current voltage, with a resistor connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectitier means, condenser means being connected in parallel with said rectifier means across said collector base circuit; circuit means connected between said pulse generator means and said collector-base circuit for application of said pulse sequences thereto; and relay means including coil means and cooperating contact means movable be tween idle and operative positions depending upon energization of said coil means and adapted to control accordingly an operating circuit that may be connect d in circuit with said contact means, said coil means being connected at one end thereof with the collector of said transistor means, whereby said coil means will be energized depending upon the pulse frequency furnished by the pulse generator means corresponding to the speed of the engine, the parameters of said various means being so chosen that the difference between the current required for sufficiently energizing said coil means for moving said contact means from idle position to operative position, and the smaller current value at which said contact means are released to return to idle position is substantially equal to the amplitude of the wave form of the energizing current derived from said pulse sequence and applied to said coil means, whereby the critical differential between engine speeds causing the change between said positions of said contact means is reduced to a minimum.

7. Impulse controlled speed-responsive relay arrangement for motor vehicles having an engine operable at varying rotary speeds and a starter motor, comprising, in combination, pulse generator means operatively connected with the engine for furnishing pulse sequence of varying frequencies corresponding to the varying speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct current voltage, with a resistor being connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectifier means, condenser means being connected in parallel with said rectifier means across said collector-base circuit; circuit means connected between said pulse generator means and said collector-base circuit for application of said pulse sequences thereto; starter relay means including a relay coil for controlling the supply of energy to the starter motor; and guard relay means including coil means and cooperating contact means movable between idle and operative positions depending upon energization of said coil means and being connected in circuit with said relay coil of said starter relay means for controlling the latter, said coil means being connected at one end thereof with the collector of said transistor means, whereby said guard relay means will be energized depending upon the pulse frequency furnished by said pulse generator means coresponding to the speed of the engine for preventing operation of the starter motor under unfavorable conditions.

8. Impulse controlled speed-responsive relay arrangement for motor vehicles having an engine operable at varying rotary speeds and a starter motor, comprising, in combination, pulse generator means operatively connected with the engine for furnishing pulse sequences of varying frequencies corresponding to the varying speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct current voltage, with a resistor being connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectifier means, condenser means being connected in parallel with said rectifier means across said collectorbase circuit; circuit means connected between said pulse generator means and said collector-base circuit for application of said pulse sequences thereto; staner relay means for controlling the supply of energy to the starter motor, said starter relay means having a relay coil of high inductivity; second circuit means operatively connecting at least one terminal of said relay coil with said condenser means of said collector-base circuit for applying to said condenser means voltage pulses inductively produced in said relay coil at the moment of its de-energization and for thereby increasing the charge of said condenser means at such moment; and guard relay means including coil means and cooperating contact means movable between idle and operative positions depending upon energization of said coil means and being connected in circuit with said relay coil of said starter relay means for controlling the latter, said coil means being connected at one end thereof with the collector of said transistor means, whereby said guard relay means will be energized depending upon the pulse frequency furnished by said pulse generator means corresponding to the speed of the engine for preventing operation of the starter motor under unfavorable conditions.

9. An arrangement as claimed in claim 8, wherein said second circuit means comprise a series-combination of resistor means and rectifier means.

10. An arrangement as claimed in claim 9, wherein one end of said series-combination is connected to one terminal of said relay coil, While the other terminal thereof is connected to electrical ground.

11. An arrangement as claimed in claim 9, wherein said transistor means is of the p-n-p type, and wherein a starter switch is provided for connecting one terminal of said relay coil via said guard relay contact means with electrical ground and thereby to the negative terminal of said source, said series-combination being connected between said one terminal of said relay coil and the base of said transistor means as well as to one side of said condenser means, while the other terminal of said relay coil is directly connected with the positive terminal of said source.

12. An arrangement as claimed in claim 9, wherein said transistor means is of the n-p-n type, and wherein a starter switch is provided for connecting a first terminal of said relay coil via said guard relay contact means with the positive terminal of said source, said series-combination being connected between said first terminal of said relay coil and one side of said condenser means, while the second terminal of said relay coil is directly connected to electrical ground and thereby to the negative terminal of said source.

13. Impulse controlled speed-responsive relay arrangement for motor vehicles having an engine operable at varying rotary speeds and a starter motor, comprising, in combination, pulse generator means operatively connected with the engine for furnishing pulse sequences of varying frequencies corresponding to the varying speeds of the engine; transistor means having an emitter-base circuit connected between the terminals of a source of direct cur rent voltage, with a resistor being connected in said circuit between the base of said transistor means and one of said terminals, and having a collector-base circuit containing rectifier means, condenser means being connected in parallel with said rectifier means across said collectorbase circuit; circuit means connected between said pulse generator means and said collector-base circuit for application of said pulse sequences thereto, said circuit means comprising transformer means having a first and a second primary Winding and a secondary winding, said first primary winding being connected in circuit with said pulse generator means, said secondary winding being connected in said collector-base circuit; starter relay means for controlling the supply of energy to the starter motor, said starter relay means having a relay coil of high inductivity; second circuit means including a series-combination of resistor means and rectifier means connected between said second primary winding and at least one terminal of said relay coil for applying through said secondary Winding to said condenser means voltage pulses inductively produced in said relay coil at the moment of its de-energization and for thereby increasing the charge of said condenser means at such moment; and guard relay means including coil means and cooperating contact means movable between idle and operative positions depending upon energization of said coil means and being connected in circuit with said relay coil of said starter relay means for controlling the latter, said coil means being connected at one end thereof with the collector of said transistor means, whereby said guard relay means will be energized depending upon the pulse frequency furnished by said pulse generator means corresponding to the speed of the engine for preventing operation of the starter motor under unfavorable conditions.

14-. An arrangement as claimed in claim 13, wherein a starter switch is provided for connecting said one terminal of said relay coil v-ia said guard relay contact means with the positive terminal of said source, while the other terminal of said relay coil is directly connected to electrical ground and thereby to the negative terminal of said source, said rectifier means being connected at the input side thereof with one end of said second primary winding.

Wintsch Sept. 9, 1941 Harman et al. June 14, 1960 

